THE FERROMAGNETIC P-D EXCHANGE IN DILUTED MAGNETIC SEMICONDUCTORS

The antiferromagnetic type of the interaction between the GAMMA(s)-band electrons and the Mn2+ ions in A(II)B(IV) diluted magnetic semiconductors has been explained by invoking the p-d hybridization mechanism. In this paper it is shown that for particular electronic configurations of the magnetic ions in diluted magnetic semiconductors the p-d hybridization can lead to a ferromagnetic interaction between the valence-band electrons and the localized spins. This happens when all the one-electron d-orbitals which hybridize with p-band states are empty (e.g., as in Sc2+ and Ti2+ ions). The appropriate p-d Hamiltonian is derived and the ferromagnetic exchange constants are evaluated.